The present invention is directed to link chains and, more particularly, to a chain connecting pin extracting apparatus that may be used to remove a connecting pin that connects the links together.
Chain connecting pin extractors are tools used when modifying or replacing chains of the type that have alternating first and second link pairs pivotably connected together by a series of connecting pins. As shown in FIG. 4(A), for example, a narrow chain 50 may comprise pairs of outer links 51 that alternate with pairs of inner links 52 in an overlapping manner. A connecting pin 53 extends through aligned openings in the outer links 51 and inner links 52 to pivotably connect them together. Ring-shaped recesses 51a and 51b are formed on the outer sides of outer links 51, and expanded portions 53a and 53b of connecting pin 53 are crimped into the respective recesses 51a and 51b in order to securely join the links together. As a result, the diameters of the ends of connecting pin 53 are greater than the diameter of the central portion of connecting pin 53. A roller 54 surrounding connecting pin 53 is rotatably supported by the inner link 52. Because connecting pin 53 is crimped into recesses 51a and 51b of outer links 51, it is less likely to protrude beyond the sides of outer links 51, thus further reducing the width of chain 50.
A chain connecting pin extractor typically removes the connecting pin of a closed-loop chain so that the links connected by the connecting pin may be separated to thereby open the loop. A chain connecting pin extractor used to modify or replace a bicycle chain is disclosed at page 205 of Shimano 2003 Bicycle Components, a retail sales manual published by Shimano Inc.
Conventional chain connecting pin extractors comprise a main body, a pin extractor and a handle component used to operate the pin extractor. The main body has a female threaded component and a link support, wherein the female threaded component is aligned with the connecting pin when the chain is mounted to the main body, and the link support supports the outer link of the chain in the axial direction of the connecting pin. The handle component has a male threaded component that screws into the female threaded component, and the pin extractor is detachably connected to the tip of the male threaded component. A diameter of a tip of the pin extractor is smaller than a diameter of the connecting pin, and a diameter of the portion of the pin extractor that connects to the male threaded component is larger than the diameter of the tip.
To use the chain connecting pin extractor, the chain is mounted to the main body such that the connecting pin that is to be removed faces the pin extractor. Turning the handle component causes the pin extractor to press against and move the connecting pin while the chain is prevented from moving by the link support. The links may be disconnected when the connecting pin is removed from at least the outer link that faces the handle component.
In the bicycle field, a chain may be used with sprocket clusters having as many as ten sprockets, wherein a derailleur is used to switch the chain among the individual sprockets. Because the sprocket cluster must fit in the limited axial space between the bicycle frame components that straddle the rear wheel, a larger number of sprockets results in narrower gaps between the sprockets, so the chain also must be thinner. A chain such as the one described above, wherein the connecting pin does not protrude axially outward from the outer links, may be used for this purpose
When the links of such narrow chains are disconnected using a conventional chain connecting pin extractor, the expanded portion of the connecting pin that faces the pin extractor sometimes breaks off from the remainder of the connecting pin, thus leaving a ring-shaped residue in the ring-shaped recess in the outer link. This residue makes it difficult if not impossible to insert a replacement pin, so the residue must be removed using a different tool.